The present invention relates to a fuel pump for use in an inter-cylinder direct fuel injection apparatus for an automobile.
There has been conventionally used an inter-cylinder direct fuel injection apparatus in a gasoline engine for an automobile in order to enhance fuel economy characteristics, reduce a harmful exhaust gas, and improve an operating responsiveness such as acceleration.
From the viewpoint of energy saving provided by the reduction of the weight of the automobile, a product is desired in which the reduction of the weight should be achieved by using an aluminum based material also in a fuel pump member in the inter-cylinder direct fuel injection apparatus.
Japanese Patent Laid-open No. 7-48681 discloses the technique by which a metallic coating film is formed on aluminum or an aluminum alloy by electroless plating, and thereafter, is subjected to electric plating.
However, since the electric plating also is used in addition to the electroless plating in the technique disclosed in Japanese Patent Application Laid-open No. 7-48681, no coating film may be formed in a region in which the electricity cannot flow very well when the technique is applied to an inter-cylinder direct fuel injection apparatus having numerous holes or narrow gaps as it is. Then, a base is exposed, thereby producing a problem of occurrence of damage such as corrosion.